R E V I E W Open AccessTooth loss and oral health-related quality of life: a systematic review and meta-analysis Anneloes E Gerritsen1*, P Finbarr Allen2, Dick J Witter1, Ewald M Bronkho
Trang 1R E V I E W Open Access
Tooth loss and oral health-related quality of life: a systematic review and meta-analysis
Anneloes E Gerritsen1*, P Finbarr Allen2, Dick J Witter1, Ewald M Bronkhorst3, Nico HJ Creugers1
Abstract
Background: It is increasingly recognized that the impact of disease on quality of life should be taken into
account when assessing health status It is likely that tooth loss, in most cases being a consequence of oral
diseases, affects Oral Health-Related Quality of Life (OHRQoL) The aim of the present study is to systematically review the literature and to analyse the relationship between the number and location of missing teeth and oral health-related quality of life (OHRQoL) It was hypothesized that tooth loss is associated with an impairment of OHRQoL Secondly, it was hypothesized that location and distribution of remaining teeth play an important role in this
Methods: Relevant databases were searched for papers in English, published from 1990 to July 2009 following a broad search strategy Relevant papers were selected by two independent readers using predefined exclusion criteria, firstly on the basis of abstracts, secondly by assessing full-text papers Selected studies were grouped on the basis of OHRQoL instruments used and assessed for feasibility for quantitative synthesis Comparable outcomes were subjected to meta-analysis; remaining outcomes were subjected to a qualitative synthesis only
Results: From a total of 924 references, 35 were eligible for synthesis (inter-reader agreement abstracts = 0.84 ± 0.03; full-texts: = 0.68 ± 0.06) Meta-analysis was feasible for 10 studies reporting on 13 different samples,
resulting in 6 separate analyses All studies showed that tooth loss is associated with unfavourable OHRQoL scores, independent of study location and OHRQoL instrument used Qualitative synthesis showed that all 9 studies
investigating a possible relationship between number of occluding pairs of teeth present and OHRQoL reported significant positive correlations Five studies presented separate data regarding OHRQoL and location of tooth loss (anterior tooth loss vs posterior tooth loss) Four of these reported highest impact for anterior tooth loss; one study indicated a similar impact for both locations of tooth loss
Conclusions: This study provides fairly strong evidence that tooth loss is associated with impairment of OHRQoL and location and distribution of tooth loss affect the severity of the impairment This association seems to be independent from the OHRQoL instrument used and context of the included samples
Background
It is increasingly recognized that the impact on quality of
life (QoL) of disease and treatment of disease and its
con-sequences should be taken into account when assessing
health status and evaluating treatment outcomes Clinical
indicators only are not sufficient to describe health status
and it has been reported that people with chronic
dis-abling disorders can perceive their quality of life as better
than healthy individuals, i.e., poor health or presence of disease does not inevitably mean poor quality of life [1,2] Adaptive capacity and personal characteristics appear to influence patient’s response to chronic disease This can result in reports which seem counterintuitive, for example, the finding in a large German survey that having fewer than 9 teeth had more impact on health-related QoL than having cancer, hypertension, or allergy [3] Therefore, clin-ical indicators only are not sufficient to describe health status This is also true for oral diseases and its conse-quences for oral health-related quality of life (OHRQoL) The two most prevalent oral diseases, caries and periodon-tal disease often do not cause symptoms in early stages
* Correspondence: a.gerritsen@dent.umcn.nl
1 Department of Oral Function and Prosthetic Dentistry, College of Dental
Science, Radboud University Nijmegen Medical Centre, Philips van
Leydenlaan 25, 6525 EX Nijmegen, The Netherlands
Full list of author information is available at the end of the article
© 2010 Gerritsen et al; licensee BioMed Central Ltd This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and
Trang 2This might explain that clinical indicators of caries or
peri-odontal involvement, such as number of decayed teeth,
respectively tooth mobility and pocket depth are not
strongly associated with impairment of OHRQoL [4,5]
However, caries and periodontal disease are progressive
processes, and lead to tooth loss if not treated adequately
Tooth loss will presumably cause functional impairment,
for example, with regard to chewing and esthetics,
depending on the location of tooth loss, which might
ulti-mately affect QoL
Besides generic health related QoL measures, specific
oral health-related quality of life models and measures
have been developed to assess the impact of oral disease
on OHRQoL [6] For example Locker [7] described a
model based on the WHO classification of impairment,
disability and handicap The Oral Health Impact Profile
(OHIP), one of the most popular measures, was
devel-oped on basis of this model [8]
Although OHRQoL assessment by validated
question-naires is more common nowadays, a recent systematic
review of the literature resulted in only sparse
informa-tion regarding OHRQoL treatment outcomes of
recon-structive dentistry for partially edentate patients [9]
However, besides using OHRQoL measures to evaluate
treatment outcomes it is in the first place important to
know to what extent tooth loss actually affects OHRQoL
This enables development of clinical decision making in
public health and to provide appropriate oral health care
Several population surveys include‘number of teeth’ in
statistical models analyzing impact on OHRQoL, but this
parameter appears not always to be the most prominent
predictor For example, in a population of older adults in
Sri Lanka, Ekanayake [10] found only a weak association
between tooth loss and other clinical parameters on the
one hand and oral impacts on the other hand This
sug-gests that other factors such as age, gender or cultural
background of the patient play an important role in the
perception of health [10,11] In contrast, in a large
Japa-nese study Ide et al [12] found a strong correlation
between the number of missing teeth and higher OHIP
scores suggesting impairment of OHRQoL
The aim of the present study is to systematically
review the literature and to analyse the relationship
between the number and location of missing teeth and
oral health-related quality of life (OHRQoL) It was
hypothesized that tooth loss is associated with an
impairment of OHRQoL Secondly, it was hypothesized
that location and distribution of remaining teeth play an
important role in this
Methods
Search strategy
In this study the Cochrane guidelines for the conduct of
a systematic review were used [13] Medline, PubMed,
Embase and the Cochrane Library were initially searched for papers published from 1990 to June 2008
to answer the following question: is tooth loss associated with impairment of people’s oral health related quality
of life and what is the role of location and distribution
of tooth loss in this relationship? The search was updated in July 2009 A broad search strategy was pur-sued to capture as many relevant studies as possible For this reason not only studies with subject matter ‘tooth loss’ but also studies with subject matter ‘management
of tooth loss’ were searched for The following keywords were used: ‘quality of life’, ‘patient satisfaction’, ‘tooth loss’, ‘partial edent*’, ‘partial denture’, ‘implant’ and
‘prosthodont*’ MeSH terms were used if the search machine of the database permitted this The full search strategy for PubMed is presented in Table 1 As in the early nineteen nineties quality of life was not a general used concept in dentistry, patient satisfaction was used
as a proxy of quality of life Although RCT’s provide the highest level of evidence, this study design is in most cases not feasible for tooth loss Therefore, data from observational studies like cross-sectional studies, case series, case-control and cohort studies are included in this review [14] Only publications in English were selected Reference lists of the eventually included papers were hand-searched to identify additional rele-vant studies and possible false exclusions, until no new applicable titles appeared (saturation)
Study selection Two readers (NHJC and AEG) independently selected references on the basis of titles and abstracts for the impact of tooth loss or tooth replacement on oral health-related quality of life using predefined exclusion criteria Excluded were case reports, (narrative) reviews, non-human studies, non-oral implants (hip/knee) studies, stu-dies exclusively dealing with edentulous subjects/full (over)dentures, restorations not replacing teeth, ortho-dontics, perioortho-dontics, tooth wear, and medical compro-mised patient groups (e.g irradiated patients and systemic diseases like diabetes) The readers were
Table 1 PubMed search as used
#1 ("Quality of Life"[MeSH]) OR ("Patient Satisfaction"[MeSH])
#2 ("Denture, Partial"[MeSH]) OR ("Denture, Partial, Fixed"[MeSH]) OR ("Dental Implants"[MeSH]) OR ("Dental Implants, Single-Tooth"[MeSH]) OR ("Dental Prosthesis, Implant-Supported"[MeSH])
OR ("Osseointegration"[MeSH]) OR ("Dental Implantation"[MeSH])
#3 ("Jaw, Edentulous, Partially"[MeSH]) OR ("Tooth Loss"[MeSH])
#4 (#1 AND #2)
#5 (#1 AND #3)
#6 (#4 OR #5)
Trang 3calibrated by discussion sessions after assessment of
every 10 abstracts If necessary, the list of excluding
cri-teria was revised after a discussion session and those
abstracts already screened were re-subjected to the
selec-tion process This procedure was repeated until no new
exclusion criteria turned up Agreement between readers
was determined using statistics Disagreements were
resolved by discussion and if not resolved a third reader
was called in (PFA) and reviewed the manuscript
inde-pendently In cases of doubt, the reference was included
This approach was applied in all selection steps
After abstract selection, full-text copies of the selected
papers were made These full-text papers were assessed
independently by the two readers (NHJC and AEG)
using a pilot-tested assessment form Full-text paper
exclusion criteria are outlined in Table 2 In this phase
of the review process, if considered necessary, authors
were contacted to clarify issues of their published
research that gave rise to uncertainty
Synthesis of data
Studies were grouped on the basis of OHRQoL
instru-ments used: Oral Health Impact Profile (OHIP), Oral
Impact on Daily Living (OIDP), Geriatric Oral Health
Assessment Index (GOHAI), Dental Impact of Daily
Liv-ing (DIDL), OHQoL-UK©, and others The rationale for
this grouping was the incompatibility of the various
instrument scoring systems Besides that, the
categoriza-tions of number of teeth as used in the original studies
should be comparable Subsequently, for studies
pre-senting continuous outcomes (e.g mean scores)
meta-analysis was deemed possible if a variance estimate was
presented such as SD or SE For studies presenting
dichotomized outcomes pooling was considered possible
if numbers with or without outcome property (e.g with
or without impact) were presented
For continuous data Cochran’s Q [15] was calculated
to test for heterogeneity Summary effects were calcu-lated with DerSimonian’s method [16] in case of hetero-geneous data and weighted average was calculated for homogeneous data
For dichotomized data Woolf’s test [17] for heteroge-neity was used Again, summary effects were calculated
by DerSimonian’s method [16] in case of heterogeneous data, but the Mantel-Haenszel test [18] was used for homogenous data
All studies, including those not suitable for meta-analyses, were subjected to qualitative analyses For qualitative analyses study characteristics, main out-comes concerning missing teeth and possible other relevant outcomes were extracted and grouped accord-ing to OHRQoL instrument used
Results
Study selection and study characteristics Details of the identification, screening and selection pro-cess are presented in Figure 1 A total of 396 references was identified through the searching of Medline, 516 through PubMed, 134 through Embase, and 149 through
Table 2 Exclusion criteria applied for eligibility
assessment of full-text papers and number of exclusions
Reason for exclusion (eligibility) Number of studies
excluded Incomplete sample information 10
• Sampling method unclear
• Age distribution not stated
• Gender distribution not stated
Insufficient methods (information) 26
• No clinical examination or validated ‘self
tooth count ’ form not used
• Measure for satisfaction or OHRQoL not
clearly described
• Details of replacement not explicit
OHRQoL outcomes not related to (management
of) tooth loss
73 Mistakenly included on the basis of abstract 20
Figure 1 Flow chart outlining the search strategy and results along various steps.
Trang 4the Cochrane Library Duplicate references were removed
and eventually 783 references remained The search
update resulted in 141 additional abstracts For abstract
assessment complete agreement was seen for 884
abstracts (inter-reader agreement = 0.84; SE = 0.03)
and consensus was reached in 40 cases (23 included, 17
excluded) After reviewing the abstracts, 150 studies were
included in the study Reference tracking revealed 24
additional papers adding up to a total of 174 full-text
papers for eligibility assessment Finally, after assessment
of full-text articles, 45 papers were included for review
(inter-reader agreement = 0.68; SE = 0.06) In 5 cases
the third reader’s judgement was decisive As the present
study is only dealing with tooth loss, and not with
man-agement of tooth loss, studies exclusively dealing with
the latter were not used for the present analyses
Charac-teristics and main outcomes of the 35 remaining studies
[4,5,10,12,19-49] are presented in Additional file 1, Table
S1; a summary of the data and feasibility for meta-analy-sis are presented in Additional file 2, Table S2
Quantitative analyses
In summary, 10 studies reporting on 13 different sam-ples were eligible for meta-analysis resulting in 6 sepa-rate syntheses on the outcomes of 4 OHRQoL instruments (Table 3, Figures 2, 3, 4, 5, 6, 7)
Oral Health Impact Profile (OHIP) studies Two studies [25,43] reported OHIP data as mean total scores (SD) from three different samples of three cross-sectional surveys from the UK (n = 3662), Australia (n = 3406) and Finland (n = 5987) In this analyses mean OHIP scores of subjects with 25-32 teeth were compared with mean OHIP scores of subjects having 21-24 teeth, 17-20 teeth, 9-16 teeth and 1-8 teeth (Figure 2) Data are presented as differences in mean OHIP scores per group for each sample This meta-analysis shows that the fewer Table 3 Summary of the 6 meta-analyses
Comparison Summary effect 95% CI p-value for heterogeneity test Model used Meta analysis 1 [25,43]
Continuous data (difference in mean OHIP total scores)
Total n = 12,965
Reference group: 25-32 teeth
1-8 teeth 3.37 1.37-5.38 <0.001 random effect 9-16 teeth 3.08 1.37-4.80 <0.001 random effect 17-20 teeth 1.89 -0.03-3.82 <0.001 random effect 21-24 teeth 1.05 0.07-2.02 <0.001 random effect Meta analysis 2 [25,26]
Dichotomized data (Odds ratio for having an OHIP impact)
Total n = 6821
Reference group: complete dentition or ≥ 25 teeth
Incomplete or < 25 teeth 3.45 2.93-4.05 0.975 fixed effect
Meta analysis 3 [5,24,45]
Dichotomized data (Odds ratio for having an OIDP impact)
Total n = 2204
Reference group ≥ 21 teeth
≤ 10 teeth 2.01 1.43-2.83 0.962 fixed effect
>10 and <21 teeth 1.63 1.23-2.17 0.794 fixed effect
Meta analysis 4 [5,45]
Dichotomized data (Odds ratio for having an OIDP impact)
Total n = 1184
Reference groups 9-16 NOPs/4-8 POPs/no UAS
0-8 NOPs 1.99 1.39-2.86 0.279 fixed effect
0-3 POPs 1.66 1.16-2.37 0.808 fixed effect
UAS 1.82 0.68-4.87 0.025 random effect Meta analysis 5 [38,46]
Continuous data (difference in mean GOHAI total scores)
Total n = 435
Reference group: 20-32 teeth
0-19 teeth 9.78 7.38-12.18 0.157 fixed effect
Meta analysis 6 [31,35]
Continuous data (difference in mean OHQoL-UK total scores)
Total n = 2738
Reference group: 20-32 teeth
0-19 teeth 4.56 3.67-5.44 0.912 fixed effect
Trang 5teeth are present the higher the impact on OHRQoL with
a marked deterioration once the number of remaining
teeth drops below 17
Two studies [25,26], including in total 6,821 subjects,
reported OHIP data as prevalence of impacts according
to dental status (Figure 3) One study categorized dental
status as complete dentition vs one or more missing
teeth [26] whereas the other study categorized dental status as 32-25 teeth vs 0-24 teeth [25] This pooling was made on the assumption that categories were com-parable Differences in impact scores between the two categories in each study are presented as Odds Ratios The pooled data indicate that loss of teeth is associated with a threefold likelihood of reporting an impact on OHRQoL
Oral Impact on Daily Living (OIDP) studies The three studies [5,24,45], including in total 2204 sub-jects, that used OIDP scores as an outcome measure for OHRQoL are presented in Figure 4 In all three studies OIPD scores were calculated by multiplying frequency
by severity of the impact and summing up the scores of ten areas of daily activities Three categories of dental status were presented namely 0/1-10, 11-20 and 21-32 teeth present Differences between the categories were presented as Odds Ratios with having an impact as dependent variable Subjects with fewer than 10 teeth were twice as likely to report an impact compared with subjects having 21-32 teeth; subject with 11-20 teeth were 1.5 times more likely to report an impact
Two of the OIDP studies [5,45] (total number of sub-jects = 1184) presented OHRQoL data in relation to occluding pairs and location of tooth loss: natural occluding pairs (NOPs), posterior occluding pairs (POPs), and presence of ‘unrestored anterior spaces’ (UAS) Differences between categories are presented as Odds Ratio’s with having an impact as dependent vari-able (Figure 5) Reporting an impact on their daily life was twice as likely for subjects with 0-8 NOPs than for subjects having 9-16 NOPs and 1.6 times more likely for subjects having 0-3 POPs than for subjects having 4-8
Figure 2 Synthesis of two studies presenting differences in
mean OHIP total scores Forest plots presenting differences in
mean OHIP total scores of categories of number of present teeth
for three samples (total n = 12,965) [25,43] The category 25-32
teeth was used as reference Relative box size indicates the weight
of the study: (a) 1-8 teeth (heterogeneity Q = 16.75; df = 2), (b)
9-16 teeth (heterogeneity Q = 17.80; df = 2), (c) 17-20 teeth
(heterogeneity Q = 22.06; df = 2), (d) 21-24 teeth (heterogeneity
Q = 15.51; df = 2).
Figure 3 Synthesis of two OHIP studies presenting Odds
Ratio ’s Forest plot presenting Odss Ratio’s (OR) for having OHIP
impacts (fairly/very often) of two categories of number of present
teeth (incomplete vs complete [26] and ≤ 24 vs ≥ 25 [25]) in two
samples (total n = 6821) Relative box size indicates weight of the
study (heterogeneity Χ 2 = 0,00; df = 1).
Figure 4 Synthesis of three OIDP studies presenting Odds Ratio ’s Forest plots presenting Odss Ratio’s (OR) for having any impact on OIDP of three categories of number of present teeth in three samples (total n = 2204) [5,24,45] Relative box size indicates weight of the study (a) ≤ 10 vs ≥ 21 (heterogeneity Χ 2 = 0.08;
df = 2), (b) >10 and < 21 vs ≥ 21 teeth (heterogeneity Χ 2 = 0.46;
df = 2).
Trang 6POPs Subjects having one or more unrestored anterior
spaces were 1.8 times more likely to report any impact
on their daily life
Geriatric Oral Health Assessment Index (GOHAI) studies
The two GOHAI studies [38,46] (total n = 435) in this
meta-analysis used mean total scores as outcome
mea-sure (Figure 6) Differences in the mean scores show
that GOHAI scores were higher for subjects with 20 or
more teeth, indicating better OHRQoL
Oral Health Quality of Life-UK (OHQoL-UK©)studies
Two studies [31,35] reported mean total scores for
OHQoL-UK© for four different samples from the UK,
Syria, Egypt and Saudi Arabia with a total of 2783
sub-jects (Figure 7) Differences between mean total scores
of two categories of dental status, namely 0-19 teeth presentvs 20 and more teeth It should be noted that the UK sample contributes 91% to the summary effect Qualitative analyses
The studies that failed the criteria for meta-analysis were only analyzed qualitatively
Number of teeth Most included studies found statistically significant asso-ciations between missing teeth and unfavourable OHQoL scores, independent of the instrument used or the country of investigation However, the results of a
Figure 5 Synthesis of two OIDP studies presenting Odds Ratio ’s in relation to occluding pairs and location Forest plots presenting Odss Ratio ’s (OR) for having any impact on OIDP of two categories of number of natural occluding pairs (NOPs) and posterior occluding pairs (POPs) and unrestored anterior spaces (UAS) in two samples (total n = 1184) [5,45] Relative box size indicates weight of the study (a) NOPs 0-8 vs 9-16 (heterogeneity Χ 2
= 1.17; df = 1), (b) POPs 0-3 vs 4-8 (heterogeneity Χ 2
= 0.06; df = 1), (c) UAS yes vs no (heterogeneity Χ 2
= 5.03; df = 1).
Figure 6 Synthesis of two studies presenting differences in
mean GOHAI total scores Forest plot presenting differences in
mean GOHAI total scores between two categories of number of
present teeth: 0-19 teeth vs 20+ teeth in two samples (total n =
435) [38,46] Relative box size indicates weight of the study
(heterogeneity Q = 2.00; df = 1).
Figure 7 Synthesis of two studies presenting differences in mean OHQoL-UK©total scores in four samples Forest plot presenting differences in mean OHQoL-UK©total scores between two categories of numbers of present teeth: 0-19 teeth vs 20 and more teeth in four samples (total n = 2738) described in two studies [31,35] Relative box size indicates weight of the study (heterogeneity Q = 0.15; df = 3).
Trang 7few studies were not conclusive: Hassel [23] reported no
statistically significant difference in OHIP scores
between dentate and edentate institutionalized elderly,
but statistically significant higher OHIP scores for
sub-ject with ‘less teeth in static occlusion’; Mesas [37]
reported only statistically significant differences in
GOHAI scores between edentulous and dentate subjects
for the‘physical’ dimension but not for the ‘social’ and
‘worry’ dimension; Tsakos [5] and Sheiham [41],
report-ing on the same sample, found no statistically significant
association between number of present teeth and having
an OIPD impact in British adults, but lower numbers of
anterior occluding pairs and natural occluding pairs
were associated with OHRQoL impairment
Occluding pairs and location of missing teeth
Statistically significant positive correlations between
number of occluding pairs and OHRQoL were found in
all 10 studies (dealing with 9 different samples) reporting
on this subject [5,20,21,23,27,29,36,37,44,45] (Table 4)
Five studies reported on OHRQoL and location of
missing teeth, four of them [5,40,45,48] reporting higher
impact for missing anterior teeth One of them [44]
indicated comparable impact for missing posterior
occluding pairs and anterior occluding pairs (Table 5)
Discussion
Chronic diseases such as dental caries are still highly
prevalent in older adults, and the risk of tooth loss in
old age is high Oral health care with an intervention
led focus is costly, and demand for this care may
increase as the proportion of older dentate adults
increases Demand for treatment is not well correlated
with objectively determined treatment need, and it has
been recognized that objective measures of disease are
not good predictors of demand It would appear that
loss of teeth is not as acceptable as in previous
genera-tions, and this will potentially influence future demand
for treatment [50] As public resources for dental
treat-ment becomes increasingly scarce, new paradigms for
assessment of oral health have been developed The use
of OHRQoL measures has increased significantly over
the past 15 years By incorporating subjective and
objec-tive assessment, our understanding of the consequences
of oral disease and tooth loss has improved [51]
Subjec-tive assessment has also been advocated as a means of
targeting treatment resources provided through
publi-cally funded health services [52] The rationale for this
is to prioritise scarce financial resources towards those
eligible patients most likely to benefit from a particular
therapy It is known that the impact of disease on
qual-ity of life is highly variable, and thus, the impact of a
treatment intervention will also vary An example of this
is in the use of dental implants to retain prostheses in
edentulous patients Dental status (in this case, edentate)
does not necessarily predict treatment outcome, and edentate patients satisfied with having complete den-tures are unlikely to report significant extra benefit from having an expensive intervention (e.g., implant retained dentures) [53] In this scenario, a health service provider would prefer to target resources towards patients who are dissatisfied with being edentate and have a poor self-reported health status This is particularly relevant where a cure is not the objective of treatment, and the treatment goal is a reduction in morbidity associated with chronic disease
Individual studies that have reported OHRQoL out-comes have indentified predictors of poor OHRQoL These included disease severity, dental status, social class and cultural background Unfortunately, there has been a lack of uniformity in methods used to collect these data, and this has created some difficulty in gener-alizing the results of individual studies A variety of OHRQoL measures have been used, ranging from ad hoc, non-validated questionnaires (mostly used in the early nineteen nineties when quality of life was not a general used concept in dentistry yet), to comprehensive measures based on conceptual models and validated for use in particular populations In the case of the latter measures, scoring systems have varied and been reported variously as prevalence, severity, and combina-tions of negative and positive percepcombina-tions of health Finally, population studies have for the most part used shortened versions of validated measures such as the OHIP and this may lead to under-reporting of impacts Given these concerns, this review of the literature aimed to assimilate all of the available information on the relationship between tooth loss and OHRQoL in a systematic way using existing guidelines for conducting
a systematic review There were some limitations com-mon to most systematic reviews, primarily difficulty in accessing literature not published in English In order to minimize the possibility of publication bias, authors with acknowledged expertise in the field were contacted
to determine if they had relevant data, which had not yet been published They were also asked to clarify issues in their published research, which gave rise to uncertainty during the data extraction phase of the review Accordingly, we believe that we have minimized the impact of reporting and publication bias
Quality assessment of included studies was restricted
to the use of exclusion criteria These included mini-mal criteria of sample description (age and gender dis-tribution) but not for example Socio Economic Status (SES) Other criteria indicating the quality of surveys, such as the number of observers, observer agreements, representativeness for larger samples, and the use of validated instruments were not always described, but were not used in the exclusion process For instance,
Trang 8nine of the included studies were validation studies
and these studies - presenting relevant data - would
have been excluded in case the use of a validated
instrument were an inclusion criterion Although these
studies were designed for another purpose, i.e to test
the psychometric properties of newly developed
OHR-QoL instruments, it was considered to be appropriate
to use data on the number of missing teeth from these
studies
As far as we are aware of, this is the first systematic
review and meta-analysis of the relationship between
OHRQoL and tooth loss Data from our systematic
review and meta-analyses of observational studies pro-vide fairly strong epro-vidence that tooth loss is, on the whole, viewed negatively This is a consistent finding, and appears to be independent of the OHRQoL measure used to assess subjective impact and context (e.g., coun-try of residence) However, the severity of impairment of OHRQoL is probably context dependent [43] Moreover, the severity of impairment might be associated with location and distribution of missing teeth, as suggested
by the outcome of the meta-analysis of data of a Greek and a British population (Figure 5) Although associated, the correlation between number of missing teeth and
Table 4 Summary of studies reporting on occluding pairs
First author, year Population, sample n, (%
females)
Subject of the study Main outcomes regarding occluding pairs OHIP-49 (Oral Health Impact Profile)
Baba, 2008aCS[20]
Baba, 2008b CS [21]
Japanese adults with shortened dental arches
n = 155 (70)
Relationship between shortened dental arches and OHRQoL
a: Dose response relationship between number of missing posterior teeth and OHRQoL in subjects with shortened dental arches Missing posterior units is related to impairment of OHRQoL.
b: Patterns of missing occluding units likely to be related to the OHRQoL impairment in shortened dental arch subjects with the presence of first molar contact having a particularly important role.
Hassel,2006CS[23] German institutionalized
elderly
n = 159 (81)
Dental and non-dental factors
on OHRQoL of institutionalized elderly
Less teeth in static occlusion related to impairment of OHRQoL.
Locker, 1994 LT [29] Canadian older adults
n = 312 (54)
Clinical and subjective indicators of oral health status and OHRQoL
Having fewer functional units associated with impairment of OHRQoL.
GOHAI (Geriatric Oral Health Assessment Index)
Mesas, 2008CS[37] Brazilian urban elderly
n = 267 (60)
Dental and non-dental factors
on OHRQoL
Absence of posterior occlusion associated with impairment
of OHRQoL but only statistically significant for ‘physical’ dimension and not for the ‘social’ and ‘worry’ dimensions Swoboda, 2006 CS [44] American low income elderly
n = 733 (56)
Dental and non-dental predictors on OHRQoL
OHRQoL positively related to the total number of occluding pairs, molar pairs occluding, anterior pairs occluding, and premolar pairs occluding.
OIDP (Oral Impact on Daily Performance)
Tsakos, 2006CS[5] British non-institutionalized
elderly (subsample of Sheiham, 2001)
n = 736 (48)
Clinical correlates of OHRQoL OHRQoL significantly related to the total number of
occluding pairs and to the number of anterior occluding pairs but not to the number of posterior occluding pairs.
Tsakos, 2004CS[45] Greek non-institutionalized
elderly
n = 448 (64)
Relationship between clinical dental measures and OHRQoL
OHRQoL significantly related to the total number of occluding pairs and to the number of posterior occluding pairs.
Ad hoc satisfaction questionnaires
Leake, 1994CS[27] American and Canadian
older adults
n = 338 (55)
Assessment of relationship between oral function and posterior dental units
Low number of posterior units was associated with embarrassment and dissatisfaction on chewing and appearance, indicating OHRQoL impairment.
Meeuwissen, 1995 CS
[36]
Dutch dentate older adults
n = 320 (59)
Satisfaction with reduced dentitions
Fewer posterior occluding units associated with lower satisfaction scores, indicating OHRQoL impairment.
CS
= cross-sectional study; LT
= longitudinal study; CO
= cohort study; VA
= validation study
Trang 9number of occluding pairs (which is a derivative of the
distribution of missing teeth) is not linear [54]
There-fore, the impact of cultural background, and location
and distribution of missing teeth remains subject for
further exploration
It should be acknowledged that all studies are
reported at population level, and this may mask
hetero-geneity of scores at an individual level The latter is
reflected by the wide variation in outcome scores in the
meta-analyses as presented in Figures 2, 3, 4, 5, 6 and 7
Despite this, it seems that the negative view of tooth
loss may ultimately result in demand for treatment to
replace missing teeth This will include a demand for
dental implant retained restorations and other costly
forms of treatment with a high burden of maintenance
Acceptance of dental extraction and replacement of
teeth with conventional removable dentures, either
par-tial or complete, has diminished [50]; furthermore,
abil-ity to adapt to complete replacement dentures in old
age is also uncertain and best avoided if possible This
poses a considerable challenge for oral health care policy
makers, and it is unlikely that all demand for high cost
treatment interventions can be met solely by publicly
funded healthcare
The shortened dental arch concept has been described
as means of providing sub-optimal, but acceptable level
of oral function [55] In limiting treatment goals to
pro-viding a shortened dental arch, costs of care can be
minimized The results of the review suggest that the number of occluding pairs of teeth is an important pre-dictor of OHRQoL, and that the prevalence of negative impacts increases sharply once the number of teeth pre-sent drops below 20 It seems reasonable to suggest that application of the shortened dental arch approach is acceptable, particularly to older adults, and this may help inform public policy for oral health care in older age groups The data also suggest that preventive strate-gies aimed at reducing tooth loss need to be reinforced
As reported by Petersen and Yamamoto [56], most oral diseases and chronic disease share common risk factors, and national health programs should incorporate disease prevention and health promotion using a common risk factor approach Given the rising burden of chronic dis-ease in an aging population, coupled with its negative impact on quality of life, this should receive urgent attention from policy makers
Conclusions
This study provides fairly strong evidence that tooth loss
is associated with impairment in OHRQoL This asso-ciation appeared to be independent from the OHRQoL instrument used and context (e.g., cultural background)
of the included samples However, the extent and sever-ity of impairment seems to be context dependent More-over, this study indicates that not only number, but also location and distribution of missing teeth affect the
Table 5 Summary of studies reporting the location of missing teeth
First author, year Population, sample n,
(% females)
Subject of the study Main outcomes regarding location of missing teeth OHIP-49 (Oral Health Impact Profile)
Walter, 2007CS[48] Canadian rural adults
n = 140 (64)
Clinical and socio-demographic variables and OHRQoL
One or more natural posterior teeth missing not associated with OHRQoL impairment whereas one or more natural anterior teeth missing was associated with OHRQoL impairment.
OHIP-14 (Oral Health Impact Profile short version)
Pallegedara, 2008CS[40] Sinhalese non-institutionalized
elderly
n = 630 (54)
Tooth loss, denture status and OHRQoL ’Presence of anterior spaces’ more negative impact on the
OHRQoL than ‘missing posterior teeth’.
GOHAI (Geriatric Oral Health Assessment Index)
Swoboda, 2006 CS [44] American low income elderly
n = 733 (56)
Dental and non-dental predictors on OHRQoL
Comparable impact on OHRQoL of the number of molar pairs occluding, premolar pairs occluding and anterior pairs occluding.
OIDP (Oral Impact on Daily Performance)
Tsakos, 2004CS[45] Greek non-institutionalized
elderly
n = 448 (48)
Relationship between clinical dental measures and OHRQoL
Having ‘unfilled anterior spaces’ more impact on OHRQoL than having few (0-3) posterior occluding pairs.
Tsakos, 2006 CS [5] British non-institutionalized
elderly
n = 736 (64)
Clinical correlates of OHRQoL
Having few anterior occluding pairs (0-2) more impact on OHRQoL than having few posterior occluding pairs (0-3).
CS
= cross-sectional study; LT
= longitudinal study; CO
= cohort study; VA
= validation study
Trang 10severity of OHQoL impairment Given the negative
con-sequences of tooth loss on OHRQoL, it is important
that disease prevention measures are promoted when
formulating health policy for older adults It is likely
that there will be greater demand from patients for
treatment aimed at preserving teeth The effectiveness
of preventive strategies will require further research, and
further economic analysis of tooth replacement
strate-gies is also required
Additional material
Additional file 1: Table S1: Summary of primary and additional
outcomes of all included studies.
Additional file 2: Summary of data of all included studies and
feasibility for meta-analysis.
Author details
1 Department of Oral Function and Prosthetic Dentistry, College of Dental
Science, Radboud University Nijmegen Medical Centre, Philips van
Leydenlaan 25, 6525 EX Nijmegen, The Netherlands 2 Department of
Restorative Dentistry, University Dental School & Hospital, Wilton, Cork,
Ireland 3 Department of Community and Restorative Dentistry, College of
Dental Science, Radboud University Nijmegen Medical Centre, Philips van
Leydenlaan 25, 6525 EX Nijmegen, The Netherlands.
Authors ’ contributions
AEG designed the study, assessed all included publications for eligibility and
drafted the manuscript EMB performed the statistical analyses and assisted
in the interpretation of the data and helped to draft the manuscript, PFA
participated in the design of the study and assessment of the included
papers and helped to draft the manuscript, DJW helped to draft the
manuscript, NHJC participated in the design of the study, assessed all
included publications for eligibility and helped to draft the manuscript All
authors read and approved the final manuscript.
Competing interests
The authors declare that they have no competing interests.
Received: 16 July 2010 Accepted: 5 November 2010
Published: 5 November 2010
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